MB-21143: Remove adjusted-time/drift and associated code

MB-21143: Remove adjusted-time/drift and associated code

As part of simplfying the supported LWW code, remove the
adjusted-time API and associated code.

Change-Id: I4d1cb092d4fce3155d1cd1e0134333655bcb3a61
Reviewed-on: http://review.couchbase.org/67999
Reviewed-by: Dave Rigby <daver@couchbase.com>
Tested-by: buildbot <build@couchbase.com>